Abstract. In the United States, over 100,000 deep brain stimulation (DBS) devices have been implanted to date for treatment of basic tremor, Parkinson?s disease and dystonia, and clinical trials are underway to evaluate indications for chronic pain, severe depression, migraines and dementia. DBS devices belong to a class of devices called implantable electrical stimulators, and close to 1 Million of these devices are implanted annually. While effective in many cases, DBS shows limited effectiveness in others and also has side effects. Preclinical studies predict that DBS arrays comprised of many densely packed, small electrodes can more precisely target specific regions of the brain to improve therapy. Further, incorporating some electrodes which can provide sensory feedback (closed loop) may be able to improve therapy efficiency and effectiveness. These discoveries are motivating the neuromodulation industry to develop smaller, less invasive electrodes. However, current electrode materials do not support small sizes without severely restricting the stimulus output. Hence, an improved electrode material will benefit present and future DBS systems. Platinum Group Coatings LLC has developed a cost-effective and materials-efficient process for applying an ultra-low impedance platinum-iridium alloy coating onto the contacts of DBS stimulator and cortical recording electrodes. This program, in collaboration with University of Minnesota, seeks to validate the performance advantages of this coating when applied to a novel, flex circuit electrode array for DBS. Specifically, PtIr-coated thin film electrodes will be tested in bi-directional (i.e. stimulation and sensing) modalities to assess efficacy as well as material safety and stability in a non-human primate model of Parkinson?s disease. This phase-II research will seek to determine the durability and longevity of Pt-Ir coating on thin-film high-density DBS electrodes used bi-directionally to assess the long-term recording and stimulation performance of the coatings in vivo.